I have front end wobble

[mudski]

I rebuilt the whole front end on mine and had the tyres balanced on numerous times and I still have the wobbles. Not as bad but its still there. I just gave up in the end.

[BigRAWesty]

Did you do the rear??

[Bloodyaussie]

Amazing how many times people think its the front when its really coming from the rear.....

For me just about everytime I get the wobbles its been tyres...

[BigRAWesty]

Amazing how many times people think its the front when its really coming from the rear.....

For me just about everytime I get the wobbles its been tyres...

Yep. Very overlooked area..

[Chubba]

Front end wobble at highway speed was my steering dampener. replaced and no more wobble.

[dodgypatrol]

Front end wobble at highway speed was my steering dampener. replaced and no more wobble.

I just got my patrol back and the guys who did the wheel alignment reckon that the steering will never be 100% at 0 or get rid of the highway shudders unless i add a second steering dampener also.

Any ideas on pricing or who is the best group to see about having this sorted at a decent price?

regards, Jarryd.

[BigRAWesty]

Bs mate. I'm currently using no dampener and no caster correction on the radius arms..
Everything has to be 100%..

[Robo]

out of round tyres if all else is good.
and check the rims also for out of round.
if rims have a wobble that's most likely the cause of tyre failure,
try jacking up , spin wheel and observe tread for uneven ware,
a tyre balancing machine is good for visually checking the rim ( tyre removed of course is optimal way).
this has been my experiance.

the caster and panhards,busher etc can, and do all cause these problems,
but they tend to hide camouflage the rim and or tyre problem.

m2cw I tend to think that's why so many of us have trouble narrowing it down, after we check all obvious items.
how often do we examine a tyre or rim! next to never.

read on Old Mav has added a whole lot of info on the subject and as usual he seems to know his stuff.
Dam I live in the wrong state!

[threedogs]

My wobble was wheel bearings, all sorted.
good as gold now

[OldMav]

Ok another subject I don't write about much due to the very odd ideas so many people have and seem to be a expert with but have no real idea of the maths or the dynamics or the science and engineering require to even gets a small perspective of. I am no expert but for a few book smarts because I wanted to know how the limited educated monkey on the wheel alignment machine could possible have any farken clue when he try's to tell me why my Nissan get the wobbles, and usually its just dribble being sprued from his no idea brain. In the US this subject is a 4 year degree course yet the kid on the alignment machine or the suspension shop owner or tyre shop owner is a bloody expert in the industry. There is one guy called Adams who has written many texts books and suspension software, I have a few of his books plus a few others use in the degree schooling of suspension dynamics and correct steering. Its odd really because the very first page of Adams suspension dynamics text book had me totally feeling like a complete noob yet our suspension shop dude is a bloody expert mmmmm somehow I have missed something here..

Anyway rant over, time for a little tiny incite to the world of steering dynamics. but more a tiny bit of understanding of our live or beam axle Nissan. Our Nissan engineer dude who is pretty smart produced a very basic but very robust front diff for us with a few compromises. In his wisdom he didn't account for us Aussies lifting our rigs even so he still did a good job. What he did for his std height patrol was to dial in a effective geometry for the std height condition with some nice angle geometry to be quite forgiving. One of the things he did was to give the tie rod a nice Ackerman angle so the wheels give a good compromise to stability when turning up to 10 degrees. This was to compensate for the crappy caster change we get with our short radius arms. He also set some odd angles on the panhard rod in relationship to the drag link to help stability for the wheel travel used which he limited so he didn't get to much change on the rear positioned tie rod.

Now you should have a little incite to what we have and a little bit on the why because as you would expect I could write a book just on those few items mentioned here. Anyway back to wobbles which is the OP's question. Our Nissan smart dude even though he designed a smart system he didn't quite understand the effect on how critical caster and king pin inclination would become or how tight the front end would have to be using a rear tie rod with such a high Ackerman angle on the arms. What happens is if you loose caster below 2 degrees the kingpin angle on a slight turn or steering angle moves the king pin inclination contact point of the tyre on the road to far back to keep the wheels in a stable condition hence if any of your steering components are slightly loose then stability is compromised dramatically hence the start of the wobbles. Even a slight lift of the rig puts a lot of this carefully thought out geometry at risk due to the short radius arms and the huge change in caster that happens when the suspension cycles. At normal std height the engineer has all the bits within safe parameters.

But little changes we don't consider like wheel offset has a dramatic effect on our Nissan it moves the contact patch or the rotation arc of king pin incline to a different balance point on the tyre if the geometry is just a little out this sort of thing can effect the inbuilt stability of the set geometry hence more prone to the wobbles if other bits are a bit loose etc. There are so many things I can suggest or a combination of things that cause this effect. Even camber with too little caster with a loose panhard will set the balance out. Sure most shops go to great length to suggest rims and tyres and balancing on and on but these things are just stop gaps to the real combination of issues causing the issue.

Just to prove a point or a suggestion of a different perspective on another OEM who designed this type of suspension, example Range Rover early models. They have the tie rod on the back with a closed Ackerman angle they used a different sweep angle for their radius arms but have the same caster kingpin angle and camber but they do not have anything like the tenderness of the Nissan to get the speed wobbles. Or even the early model F100 same basic system tie rod on the front, but a different design to the geometry, without the tenderness.

I have had a go at this phenomena a few times when the owner has given up, I get the usual story the geometry is perfect the suspension shop said so. Setting my trusty iphone on the wheel with an alignment app and you guessed it, it has less than 2 deg of caster, the book of god says 2.5 to 3 degrees there is a reason for this otherwise the Nissan dude would not have set that spec. For example a RR is 1.5 to 3.5 degrees mmmm funny that the RR has a lot more tolerance I wonder why eh.. On one particular rig he had changed his springs and the body had 2.5 degrees of angle down to the front then he had 3 deg caster correction bushers and drop boxes and still the front end had +1.2 degrees of caster. Hence he had massive wobbles and no matter what he or the suspension shop did, it was never going to go away. It just so happens not all Nissan diff geometry set in the factory are all equal the control arm plates had been welded on with too little caster built in. We lowered the back and had to bend the radius arms to get anything like -2.5 caster and a proper camber which is fix to caster of course. Funny thing is after the adjustment all was back just like STD.

Another thing I have had to adjust to fix this issue or more to the point extend the tenderness of the front end. Our Nissan dude in his design for STD height and parameters he set the panhard rod at a angle to the drag link in plan view. This is all good if both links are level in front view but lift the rig just a bit and this geometry gets a little to far out side of our set safe parameters so out tenderness to the wobbles is increased 10 fold on slight bumps. Had they been lever and parallel say like a Range Rover or F100 then this tenderness would not be as bad. I have had to lower this on the chassis end on a 3 inch lift so the rig could have different off set rims the owner wanted to use and yes problem solved.

I could go on and on here of course but really to fix this issue there is a bit more to it than meets the eye. I am not saying just because you changed you panhard bushers or tightened your wheel bearings or kingpin bearings the problem went away end of problem. What I am saying it shouldn't matter if there is a bit of movement in the bush or bearings because there is something else or a combination of other bits that has made your rig prone to death wobbles. And for god sake don't let a suspension shop fit those damn eccentric kingpin bearings that is not a fix its a bodgy if ever there was one. And that is for another time to explain.